1. Field of the Invention
The present invention relates to a method of producing a cyclododecanone compound. More particularly, the present invention relates to a method of producing a cyclododecanone compound by an isomerization of the corresponding epoxycyclododecane compound in the presence of a catalyst comprising lithium bromide and/or lithium iodide in an inert gas atmosphere. Cyclododecanone compounds are useful as materials for producing laurolactum, dodecanedioic acids, dodecane diols and perfumes.
2. Description of the Related Art
A plurality of reports on methods of producing cyclododecanone compounds by isomerization of epoxycyclododecane compounds in the presence of a catalyst comprising an alkali metal halide have been published.
For example, German Patent (DE) No. 3,601,380 discloses a method in which cyclodeca-3,7-diene-1-one is produced in a yield of 98.7% by an isomerization reaction of 1,2-epoxycyclododeca-5,9-diene in the presence of sodium iodide catalyst in a reaction medium consisting of polyethyleneglycol. Also, German Patent (DE) No. 3,744,094 discloses a method in which cyclododecanone is produced in a yield of 94% by an isomerization reaction of an epoxycyclododecane in the presence of a lithium chloride catalyst in a reaction medium consisting of N-methylpyrrolidone and/or N,Nxe2x80x2-dimethylethyleneurea.
The prior methods mentioned above are disadvantageous in that since a polar solvent such as polyethyleneglycol or N,Nxe2x80x2-dimethylethyleneurea is employed, the recovery and decomposition of the solvent may cause the cost of the reaction to increase, and the reaction apparatus is required to have a high pressure resistant. Further, a dilution effect and a salvation effect of the polar solvent on the reaction system cause the reaction rate to decrease and the scale of the reaction apparatus to be large.
Soviet Union (SU) Patent No. 407,874 discloses an isomerization reaction of an epoxycyclododecane compound in the presence of anhydrous LiBr without using a solvent. In examples disclosed in the SU patent, it is reported that when the isomerization was carried out at a reaction temperature of 120 to 130xc2x0 C. for 18 hours or at a temperature of 200xc2x0 C. for 3 hours, the target cyclododecanone was obtained in a yield of about 100% in the former or 83.3% in the latter. In the former case, the reaction time was too long and thus the reaction conditions may not be practical. Also, in the latter case, a by-product having a high boiling temperature was produced and a discoloration of the reaction liquid was found. When the catalyst is recycled and repeatedly used, the high boiling temperature product accumulated in the reaction system causes the reaction to be affected and a specific procedure for removing the high boiling temperature product to be necessary.
It is assumed that the reaction rate can be increased by increasing the concentration of the catalyst in the reaction system. In the reaction system disclosed in the above-mentioned SU patent, the concentration of the LiBr dissolved in the reaction system was saturated, and thus a further increase in the LiBr concentration was impossible. When the reaction temperature is increased to increase the reaction rate, undesirable side reactions occur, the yield of the target product decreases, high boiling temperature substances are produced and the reaction system is discolored.
Further, Zh. Org. Khim (1990), 26(7), 1497-1500 reports that when an isomerization of epoxycyclododecane was carried out at a temperature of 150xc2x0 C. for 10 hours in the presence of a catalyst comprising lithium bromide without using a solvent, a target cyclodedecanone was produced in a yield of 96.6%, and when the same isomerization as above was carried out except that the catalyst comprised lithium iodide, and the reaction temperature and time were 150xc2x0 C. and 5 hours, the target cyclodedecanone was obtained in a yield of 91.2%. However, the report is quite silent as to the reaction atmospheric gas. In the method of the report, to increase the conversion of the starting compound to the target compound to about 100%, a long reaction time is necessary, and the long reaction time causes high boiling temperature substances to be produced.
In the case where a cyclododecanone compound is industrially produced by an isomerization of an epoxycyclododecanone compound, since the boiling temperature of the starting epoxycyclododecane compound is approximately equal to that of the target cyclodedecanone compound, usually the separation of the starting compound from the target product by distillation is extremely difficult. Thus, in order to produce the cyclododecanone compound in a high degree of purity, it is necessary to control the conversion of the epoxycyclododecane compound to approximately 100%. For this, it is absolutely necessary to increase the isomeization reaction rate. To increase the reaction rate, an increase in the reaction temperature may be tried and/or an increase in the content of the catalyst in the reaction system may be attempted.
However, as mentioned above, the increase in the reaction temperature causes undesirable side reactions to occur, high boiling temperature substances to be produced, the yield of the target cyclododecanone compound to decrease.
On other hand, to increase the conversion of the starting epoxycyclododecane compound, it may be considered to further increase the concentration of the catalyst in the reaction system. However, the increase in the catalyst concentration is not practical in consideration of the solubility of the catalyst in the reaction system and the increase in production cost of the target product due to the increase in the amount of the catalyst.
As mentioned above, the conventional methods of producing the cyclododecanone compounds by the isomerization of epoxycyclododecane compounds are unsatisfactory due to a low reaction rate, a low conversion of the starting compound, a low selectivity of the target compound, production of undesirable high boiling temperature substance, and a low efficiency.
Therefore, a new method enabling the industrial production of the target cyclododecanone compound at a high reaction rate, with a high conversion of the starting compound, with a high selectivity to the target compound and with a high efficiency, while the side reaction for the production of undesired high boiling temperature substances is controlled, is strongly demanded.
An object of the present invention is to provide a method of producing a cyclododecanone compound by isomerization of an epoxycyclododecane compound at a high reaction rate at a high conversion at a high selectivity, with a high industrial efficiency, while substantially preventing the production of high boiling temperature substances.
The inventors of the present invention made an extensive study of means for attaining the above-mentioned object, and found that when the isomerization of an epoxycyclododecane compound is carried out in the presence of lithium bromide and/or lithium iodide in an inert gas atmosphere, the target cyclododecanone compound can be produced at an enhanced reaction rate, and all the above-mentioned problems of the prior acts can be solved. The present invention has been completed on the basis of the above-mentioned finding.
The method of the present invention for producing a cyclododecanone compound comprises isomerizing an epoxycyclododecane compound in the presence of a catalyst comprising at least one member selected from the group consisting of lithium bromide and lithium iodide, without using a solvent or in a non-polar solvent, in an inert gas atmosphere.
In the method of the present invention for producing a cyclododecanone compound, the epoxycyclododecane compound is preferably selected from the group consisting of saturated and unsaturated monoepoxy-cycloaliphatic compounds having a cyclic structure formed from 12 carbon atoms and an epoxy structure formed from one oxygen atom and two carbon atoms of the 12 carbon atoms being adjacent to each other and bonded to the oxygen atom.
In the method of the present invention for producing a cyclododecanone compound, the epoxycyclododecane compound is also preferably selected from the group consisting of epoxycyclododecane, epoxycyclododecenes, epoxycyclododecadienes, and epoxycyclododecatrienes.
In the method of the present invention for producing a cyclododecanone compound, the cyclododecanone compound is preferably selected from the group consisting of saturated and unsaturated cycloaliphatic compounds having a cyclic structure formed from 12 carbon atoms and a carbonyl structure formed from an oxygen atom and one of the 12 carbon atoms bonded to the oxygen atom through a double bond.
In the method of the present invention for producing a cyclododecanone compound, the cyclododecanone compound is also preferably selected from the group consisting of cyclododecanone, cyclododecenones, cyclododecadienones and cyclododecatrienones.
In the method of the present invention for producing a cyclododecanone compound, the catalyst is preferably
The present in an amount of 0.0001 to 0.1 mole per mole of the epoxycyclododecane compound.
In the method of the present invention for producing a cyclododecanone compound, the isomerizing reaction for the epoxycyclododecane compound is preferably carried out at a temperature of 100xc2x0 C. to 300xc2x0 C.
In the method of the present invention for producing a cyclododecanone compound, the inert gas preferably comprises at least one member selected from the group consisting of helium, neon, argon, krypton, xenon, hydrogen, nitrogen, carbon monoxide, carbon dioxide, methane, and ethylene gases.
The epoxycyclododecane compound usable as a starting compound for the method of the present invention is selected from the group consisting of saturated and unsaturated monoepoxy-cycloaliphatic compounds having a cyclic structure formed from 12 carbon atoms and an epoxy structure formed from one oxygen atom and two carbon atoms of the above-mentioned 12 carbon atoms being adjacent to each other and bonded to the oxygen atom.
The C12 cyclic structure of the epoxycyclododecane compound may be saturated or may have one or more double bonds.
Particularly, the epoxycyclododecane compound is preferably selected from, for example, epoxycyclododecane, epoxycyclododecenes, epoxycyclododecadienes and epoxycyclododecatrienes, more preferably epoxycyclododecane and epoxycyclododecadienes. The epoxycyclododecane compounds having one or more double bonds include various isomers. Even in this case, there is no limitation to the locations of the double bonds and the epoxy structure as defined above, in relationship to each other, and the unsaturated epoxycyclododecane compounds may be in a cis-form or in a trans-form with respect to the epoxy group and/or the double bond. The starting material for the method of the present invention may contain two or more types of epoxycyclododecane compounds different in chemical structure from each other.
The target cyclododecanone compound of the method of the present invention is a cyclododecanone compound corresponding to the starting epoxycyclododecane compound and selected from the group consisting of saturated and unsaturated cycloaliphatic compounds having a cyclic structure formed from 12 carbon atoms and a carbonyl structure formed from an oxygen atom and one of the above-mentioned 12 carbon atoms bonded to the oxygen atom through a double bond.
Particularly, the target cyclododecanone compound of the method of the present invention is preferably selected from the group consisting of cyclododecanone, cyclododecenones, cyclododecadienones and cyclododecatrienones.
The catalyst usable for the isomerization reaction of the method of the present invention comprises at least one member selected from lithium bromide and lithium iodide. When the catalyst is practically employed for the method of the present invention, no specific pre-treatment is necessary. The lithium bromide and iodide may be anhydrous or may be hydrated. Particularly, the catalyst comprises at least one member selected from anhydrous lithium bromide, lithium bromide monohydrate, lithium bromide dihydrate, lithium bromide trihydrate, anhydrous lithium iodide, lithium iodide monohydrate, lithium iodide dihydrate, and lithium iodide trihydrate. The catalyst may be supplied in the state of an aqueous solution to the reaction.
The amount of the catalyst to be used for the reaction of the method of the present invention is established in consideration of the reaction conditions. Usually, the catalyst is preferably employed in an amount of 0.0001 to 0.1 mole, more preferably 0.001 to 0.05 mole, per mole of the epoxycyclododecane compound. If the amount of the catalyst is too small, the reaction time necessary to complete the reaction may be too long and thus industrially unsatisfactory. If the catalyst amount is too large, the production cost may be too high and thus industrially unsatisfactory.
In the method of the present invention, it is important that the catalytic isomerization reaction of the epoxycyclododecane compound is carried out in an inert gas atmosphere. In the present invention, it was found for the first time that the inert gas atmosphere enables the catalytic isomerization of the epoxycyclododecane compound to industrially produce the target cyclododecanone compound with a high efficienty, at a high reaction rate, at a high conversion of the expoxycyclododecane compound, at a high selectivity to the target cyclododecanone compound, while the production of undesired by-product having a high boiling temperature is substantially prevented.
The inert gas usable for the method of the present invention preferably comprises at least one member selected from the group consisting of helium, neon, argon, krypton, xenon, hydrogen, nitrogen, carbon monoxide, carbon dioxide, methane, and ethylene gases, more preferably nitrogen, argon and carbon dioxide gases.
In the method of the present invention, the catalytic isomerization reaction is carried out without using a solvent or in a non-polar solvent. Usually, no solvent is employed. In this case, the epoxycyclododecane compound serves as a solvent for the reaction system. Namely, in this embodiment of the method of the present invention, a reaction mixture of an epoxycyclododecane compound with a catalyst is placed in a reactor, the reactor is filled with an inert gas, and the resultant reaction system is subjected to a catalytic isomerization reaction.
The reaction of the method of the present invention may be carried out in a non-polar solvent. The non-polar solvent may comprise at least one member selected from cyclic hydrocarbons having 6 to 12 carbon atoms. The non-polar solvent is usually employed in an amount in weight not more than that of the epoxycyclododecane compound.
The reaction temperature for the method of the present invention is preferably established within the range of from 100 to 300xc2x0 C., in consideration of the composition of the catalyst. When lithium bromide is used as a catalyst, the reaction temperature is preferably in the range of from 120 to 300xc2x0 C., more preferably from 150 to 280xc2x0 C., still more preferably from 170 to 260xc2x0 C. When lithium iodide is employed as a catalyst, the reaction temperature is preferably in the range of from 100 to 300xc2x0 C, more preferably from 150 to 280xc2x0 C., still more preferably 150 to 260xc2x0 C. If the reaction temperature is too low, the reaction rate may be decreased, and the decrease in the reaction rate is industrially disadvantageous. If the reaction temperature is too high, the production of the high boiling temperature substance may be promoted.
The reaction time of the method of the present invention is variable in response to the composition and the amount of the catalyst and the reaction temperature. Usually, the reaction time is preferably not more than 10 hours.
There is no limitation to the type of the reaction system or apparatus. Namely, the isomerization reaction of the method of the present invention may be effected in a batch type reaction system or apparatus or a continuous type reaction system or apparatus. Also, there is no limitation to the reaction pressure. Namely, the reaction is usually carried out under an ambient atmospheric pressure and optionally under a reduced pressure or an increased pressure.
In the method of the present invention, since the conversion of the epoxycyclododecane compound can be controlled to approximately 100%, the target cyclododecanone compound can be isolated and refined by a usual distillation procedure, namely at a temperature of 80 to 280xc2x0 C. under a pressure of 0.0001 to 0.1 MPa.